Anti-CDK20 monoclonal antibody Made to order

Radiochemoresistance is considered the main cause of local recurrence and distant metastasis in lung cancer. However, the underlying mechanisms of radiochemoresistance remain to be uncovered. In this study, we determine the functions of cell cyclerelated kinase (CDK20) in radiochemoresistance. CDK20 is a newly identified protein kinase, which plays critical roles in cell growth and proliferation in several types of cancer. Using tandem affinity purification technology, we provide evidences that CDK20 binds to the ubiquitin ligase Kelch-like ECH-associated protein 1 (KEAP1), which targets transcriptional factor nuclear factor erythroid-2-related factor 2 (NRF2) for degradation. We show that this interaction is mediated by an evolutionarily conserved ETGE motif on CDK20. Furthermore, we demonstrate that CDK20 competes with NRF2 for KEAP1 binding, enhances the transcriptional activity of NRF2 and lowers the cellular reactive oxygen species level. Moreover, CDK20-depleted cells display impaired cell proliferation, defective G2/M arrest and increased radiochemosensitivity in lung cancer. These phenotypes induced by CDK20 knockdown are partially dependent on NRF2 inactivation. More importantly, CDK20 is overexpressed in human lung cancer tissues, as determined by immunostaining. Collectively, our results suggest that CDK20 positively modulate the KEAP1-NRF2 cytoprotective pathway to regulate tumor progression and radiochemoresistance, implying that CDK20 is a novel, promising therapeutic target for lung cancer.

Objective Myeloid-derived suppressor cells (MDSCs) contribute to tumour immunosuppressive microenvironment and immune-checkpoint blockade resistance. Emerging evidence highlights the pivotal functions of cyclin-dependent kinases (CDKs) in tumour immunity. Here we elucidated the role of tumour-intrinsic CDK20, or cell cycle-related kinase (CCRK) on immunosuppression in hepatocellular carcinoma (HCC). Design Immunosuppression of MDSCs derived from patients with HCC and relationship with CCRK were determined by flow cytometry, expression analyses and co-culture systems. Mechanistic studies were also conducted in liver-specific CCRK-inducible transgenic (TG) mice and Hepa1-6 orthotopic HCC models using CRISPR/Cas9-mediated Ccrk depletion and liver-targeted nanoparticles for interleukin (IL) 6 trapping. Tumorigenicity and immunophenotype were assessed on single or combined antiprogrammed death-1-ligand 1 (PD-L1) therapy. Results Tumour-infiltrating CD11b(+) CD33(+) HLA-DR- MDSCs from patients with HCC potently inhibited autologous CD8(+) T cell proliferation. Concordant overexpression of CCRK and MDSC markers (CD11b/CD33) positively correlated with poorer survival rates. Hepatocellular CCRK stimulated immunosuppressive CD11b(+) CD33(+) HLA-DR- MDSC expansion from human peripheral blood mononuclear cells through upregulating IL-6. Mechanistically, CCRK activated nuclear factor-kappa B (NF kappa B) via enhancer of zeste homolog 2 (EZH2) and facilitated NF-kappa B-EZH2 co-binding to IL-6 promoter. Hepatic CCRK induction in TG mice activated the EZH2/NF-kappa B/IL-6 cascade, leading to accumulation of polymorphonuclear (PMN) MDSCs with potent T cell suppressive activity. In contrast, inhibiting tumorous Ccrk or hepatic IL-6 increased interferon gamma(+) tumour necrosis factor-alpha(+) CD8(+) T cell infiltration and impaired tumorigenicity, which was rescued by restoring PMN-MDSCs. Notably, tumorous Ccrk depletion upregulated PD-L1 expression and increased intratumorous CD8(+) T cells, thus enhancing PD-L1 blockade efficacy to eradicate HCC. Conclusion Our results delineate an immunosuppressive mechanism of the hepatoma-intrinsic CCRK signalling and highlight an overexpressed kinase target whose inhibition might empower HCC immunotherapy.